Switching Frequency - Emerson Powerdrive F300 Getting Started Manual

Fire Mode - Important Warning.
When Fire Mode is active the motor overload and thermal protection are disabled, as well
as a number of drive protection functions. Fire Mode is provided for use only in
emergency situations where the safety risk from disabling protection is less than the risk
WARNING
from the drive tripping - typically in smoke extraction operation to permit evacuation of a
building. The use of Fire Mode itself causes a risk of fire from overloading of the motor or
drive, so it must only be used after careful consideration of the balance of risks.
Care must be taken to prevent inadvertent activation or de-activation of Fire Mode. Fire
Mode is indicated by a flashing display text warning "Fire mode active".
Care must be taken to ensure that parameters Pr 01.053 or Pr 01.054 are not
inadvertently re-allocated to different inputs or variables. It should be noted that, by
default, Pr 01.054 is controlled from digital input 4 and changing Pr 08.024 can re-allocate
this digital input to another parameter. These parameters are at access level 2 in order to
minimize the risk of inadvertent or unauthorized changes. It is recommended that User
Security be applied to further reduce the risk (see section 5.11 Parameter access level
and security on page 53). These parameters may also be changed via serial
communications so adequate precautions should be taken if this functionality is utilized.
8.3

Switching frequency

The default switching frequency is 3 kHz, however this can be increased up to a maximum of 16 kHz
by Pr 05.018 (dependent on drive size). The available switching frequencies are shown below.
Table 8-1 Available switching frequencies
Drive size Model
3
4
5
6
7
All
8
9A
9E
10E
11E
If the switching frequency is increased from 3 kHz the following apply:
1. Increased heat loss in the drive, which means that derating to the output current must be applied.
See the derating tables for switching frequency and ambient temperature in the Drive User
Guide.
2. Reduced heating of the motor - due to improved output waveform quality.
3. Reduced acoustic noise generated by the motor.
4. Increased sample rate on the speed and current controllers. A trade off must be made between
motor heating, drive heating and the demands of the application with respect to the sample time
required.
98
2 kHz 3 kHz 4 kHz 6 kHz 8 kHz 12 kHz
Powerdrive F300 Getting Started Guide
16 kHz
Issue Number: 5